1. Field of the Invention
The invention relates to the field of lighting and/or signaling, notably for motor vehicles. It relates more particularly to a headlight lighting module and to an associated primary optical element within this module.
2. Description of the Related Art
A motor vehicle is fitted with headlights, or headlamps, which are intended to illuminate the road ahead of the vehicle, by night or under conditions of low lighting, using an overall beam of light. These headlights, a left headlight and a right headlight, comprise one or more lighting modules designed to generate and direct an intermediate beam of light which together form the overall beam of light.
These headlights can generally be used in two lighting modes: a first “high-beam” mode producing a high beam and a second “low-beam” mode producing a low beam. The “high-beam” mode allows the road to be illuminated strongly a great distance ahead of the vehicle. The “low-beam” mode produces a more limited lighting of the road, which nevertheless offers good visibility, without dazzling other road users. The two lighting modes, “high-beam” and “low-beam” complement one another, the transition from one to the other being made according to the traffic conditions. It is known practice to create the high-beam beam by adding the low-beam beam to an additional beam, that joins onto the low-beam beam at the cutoff. The low beam is generated by illuminating only means specific to the second, “low-beam” mode, while the high beam is generated by simultaneously illuminating means specific to the second “low-beam” mode and means specific to the first, “high-beam” mode.
There is now a need, within the automotive sector, to be able to illuminate the road ahead in a “partial full-beam mode”, namely to be able to generate, within a “high-beam” beam, one or more dark regions corresponding to the places in which oncoming vehicles or vehicles driving in front are present, so as to avoid dazzling the drivers of these vehicles which at the same time illuminating the roadway over the greatest possible area. Such a function is referred to as ADB (Adaptive Driving Beam) or alternatively as “selective beam”. Such an ADB function consists in, on the one hand, automatically detecting a road user liable to be dazzled by a beam of light emitted in high-beam mode by a headlight and, on the other hand, automatically modifying the shape of this beam of light so as to create a dark zone at the place where the detected user is located, with no manual intervention on the part of the driver of the vehicle. The ADB function has many advantages: ease of use, better visibility as compared with illumination in low-beam mode, better reliability in the change of mode, greatly reduced risk of dazzling, safer driving.
Lighting modules, in which, in order to create a selective beam, optical guides are placed side by side, each one illuminated by a respective light source so that the beam of light exiting the module is broken down into contiguous regions that can be switched off or on according to instructions pertaining to the detection of a nearby vehicle, are known.
The shape and arrangement of the guides relative to one another in a headlight module need to be very precise in order on the one hand to be able to create an intermediate beam exiting the module which is uniform and smoothed when all the segments are illuminated, and in order on the other hand to be able to offer an intermediate beam that complements the intermediate beam produced at output from the other headlight. In document FR 2 999 679, the Applicant company has disclosed a monoblock primary optical element that can be incorporated into a lighting module further comprising a projection system, the primary optical element comprising guides formed as integral parts of a planar face arranged in a ball the opposite face of which is substantially spherical, the ball notably forming a correction portion that makes it possible to improve the optical efficiency of the system and to correct aberrations of the lighting module.